Passage 2
The pattern of China's foreign trade has changed substantially since the founding of the people's Republic. During the 1950s China exported agricultural products to the USSR and East European countries in return for manufactured goods and the capital equipment required for the country's industrialization program which placed emphasis on the development of heavy industry. The Great Leap Forward of 1958-1959 initially produced gains in agricultural and industrial production, but subsequently resulted in serious economic imbalances. Economic problems were 【exacerbated】 by three bad harvests with the result that national incomne and the volume of foreign trade contracted during 1960-1962.
The withdrawal cf Soviet economic and technical aid in the early 1960s caused trade to shift away from the USSR and its Comecon partners towards Japan and Western Europe. A consistent theme of China's foreign trade policies has been the strong emphasis which has been placed on developing trade relations with the Third World countries.
The growth of foreign trade was disrupted again during the Cultural Revolution (1966-1976) when agricultural and industrial production fell sharply and transportation constraints became more serious.
40.What kind of clause is introduced by "when"in the sentence of the third paragraph? An adverbial clause or an attributive one?
【正确答案】：An attributive clause.
